If you haven't heard of Breakout EDU, you need to! They have tons of digital breakout rooms for all different topics. Breakout EDU is doing a "Lock of the Day" which is great for a warm-up activity. It only has one lock that students need to unlock. You can work on it as a class or challenge the students to complete themselves. Not comfortable giving it to your students because YOU don't know how to do them, NO PROBLEM. Click on the small icon on the page for the solutions and explanations! You can also invite me into your class to teach you and your students how to do them.